When two SIM cards are inserted, only one SIM card can be set as the 4G/3G/2G SIM. The other SIM card slot only supports 2G networks. You can also configure the default card for mobile data and phone calls according to your monthly plan.
This feature is only available on dual SIM phones.
Open Settings and touch Dual card management. You can configure both SIM cards as desired.
● If you disable a SIM card, you will be unable to use it to make calls, send messages, or access the Internet.
● Select Dual SIM calling. You can configure whether you want to select a SIM card manually or use the default SIM card each time you make a call. If you choose to use the default SIM card, your phone will use that SIM card for all outgoing calls